470 lines
12 KiB
C
470 lines
12 KiB
C
/* $NetBSD: malloc.c,v 1.3 1996/09/19 06:27:11 thorpej Exp $ */
|
||
|
||
/*
|
||
* from: @(#)nmalloc.c 1 (Caltech) 2/21/82
|
||
*
|
||
* U of M Modified: 20 Jun 1983 ACT: strange hacks for Emacs
|
||
*
|
||
* Nov 1983, Mike@BRL, Added support for 4.1C/4.2 BSD.
|
||
*
|
||
* This is a very fast storage allocator. It allocates blocks of a small
|
||
* number of different sizes, and keeps free lists of each size. Blocks
|
||
* that don't exactly fit are passed up to the next larger size. In this
|
||
* implementation, the available sizes are (2^n)-4 (or -16) bytes long.
|
||
* This is designed for use in a program that uses vast quantities of
|
||
* memory, but bombs when it runs out. To make it a little better, it
|
||
* warns the user when he starts to get near the end.
|
||
*
|
||
* June 84, ACT: modified rcheck code to check the range given to malloc,
|
||
* rather than the range determined by the 2-power used.
|
||
*
|
||
* Jan 85, RMS: calls malloc_warning to issue warning on nearly full.
|
||
* No longer Emacs-specific; can serve as all-purpose malloc for GNU.
|
||
* You should call malloc_init to reinitialize after loading dumped Emacs.
|
||
* Call malloc_stats to get info on memory stats if MSTATS turned on.
|
||
* realloc knows how to return same block given, just changing its size,
|
||
* if the power of 2 is correct.
|
||
*/
|
||
|
||
/*
|
||
* nextf[i] is the pointer to the next free block of size 2^(i+3). The
|
||
* smallest allocatable block is 8 bytes. The overhead information will
|
||
* go in the first int of the block, and the returned pointer will point
|
||
* to the second.
|
||
*
|
||
#ifdef MSTATS
|
||
* nmalloc[i] is the difference between the number of mallocs and frees
|
||
* for a given block size.
|
||
#endif /* MSTATS */
|
||
*/
|
||
|
||
#define ISALLOC ((char) 0xf7) /* magic byte that implies allocation */
|
||
#define ISFREE ((char) 0x54) /* magic byte that implies free block */
|
||
/* this is for error checking only */
|
||
|
||
extern char etext;
|
||
|
||
/* end of the program; can be changed by calling init_malloc */
|
||
static char *endofpure = &etext;
|
||
|
||
#ifdef MSTATS
|
||
static int nmalloc[30];
|
||
static int nmal, nfre;
|
||
#endif /* MSTATS */
|
||
|
||
/* If range checking is not turned on, all we have is a flag indicating
|
||
whether memory is allocated, an index in nextf[], and a size field; to
|
||
realloc() memory we copy either size bytes or 1<<(index+3) bytes depending
|
||
on whether the former can hold the exact size (given the value of
|
||
'index'). If range checking is on, we always need to know how much space
|
||
is allocated, so the 'size' field is never used. */
|
||
|
||
struct mhead {
|
||
char mh_alloc; /* ISALLOC or ISFREE */
|
||
char mh_index; /* index in nextf[] */
|
||
/* Remainder are valid only when block is allocated */
|
||
unsigned short mh_size; /* size, if < 0x10000 */
|
||
#ifdef rcheck
|
||
unsigned mh_nbytes; /* number of bytes allocated */
|
||
int mh_magic4; /* should be == MAGIC4 */
|
||
#endif /* rcheck */
|
||
};
|
||
|
||
/* Access free-list pointer of a block.
|
||
It is stored at block + 4.
|
||
This is not a field in the mhead structure
|
||
because we want sizeof (struct mhead)
|
||
to describe the overhead for when the block is in use,
|
||
and we do not want the free-list pointer to count in that. */
|
||
|
||
#define CHAIN(a) \
|
||
(*(struct mhead **) (sizeof (char *) + (char *) (a)))
|
||
|
||
#ifdef rcheck
|
||
|
||
/* To implement range checking, we write magic values in at the beginning and
|
||
end of each allocated block, and make sure they are undisturbed whenever a
|
||
free or a realloc occurs. */
|
||
/* Written in each of the 4 bytes following the block's real space */
|
||
#define MAGIC1 0x55
|
||
/* Written in the 4 bytes before the block's real space */
|
||
#define MAGIC4 0x55555555
|
||
#define ASSERT(p) if (!(p)) botch("p"); else
|
||
static
|
||
botch(s)
|
||
char *s;
|
||
{
|
||
|
||
printf("assertion botched: %s\n", s);
|
||
abort();
|
||
}
|
||
#define EXTRA 4 /* 4 bytes extra for MAGIC1s */
|
||
#else
|
||
#define ASSERT(p)
|
||
#define EXTRA 0
|
||
#endif /* rcheck */
|
||
|
||
/* nextf[i] is free list of blocks of size 2**(i + 3) */
|
||
|
||
static struct mhead *nextf[30];
|
||
|
||
#ifdef M_WARN
|
||
/* Number of bytes of writable memory we can expect to be able to get */
|
||
static int lim_data;
|
||
/* Level number of warnings already issued.
|
||
0 -- no warnings issued.
|
||
1 -- 75% warning already issued.
|
||
2 -- 85% warning already issued.
|
||
*/
|
||
static int warnlevel;
|
||
#endif /* M_WARN */
|
||
|
||
/* nonzero once initial bunch of free blocks made */
|
||
static int gotpool;
|
||
|
||
/* Cause reinitialization based on job parameters;
|
||
also declare where the end of pure storage is. */
|
||
malloc_init (end)
|
||
char *end; {
|
||
endofpure = end;
|
||
#ifdef M_WARN
|
||
lim_data = 0;
|
||
warnlevel = 0;
|
||
#endif /* M_WARN */
|
||
}
|
||
|
||
static
|
||
morecore (nu) /* ask system for more memory */
|
||
register int nu; { /* size index to get more of */
|
||
char *sbrk ();
|
||
register char *cp;
|
||
register int nblks;
|
||
register int siz;
|
||
|
||
#ifdef M_WARN
|
||
#ifndef BSD42
|
||
#ifdef USG
|
||
extern long ulimit ();
|
||
if (lim_data == 0) /* find out how much we can get */
|
||
lim_data = ulimit (3, 0) - TEXT_START;
|
||
#else /*HMS: was endif */
|
||
if (lim_data == 0) /* find out how much we can get */
|
||
lim_data = vlimit (LIM_DATA, -1);
|
||
#endif /* USG */ /HMS:* was not here */
|
||
#else
|
||
if (lim_data == 0) {
|
||
struct rlimit XXrlimit;
|
||
|
||
getrlimit (RLIMIT_DATA, &XXrlimit);
|
||
lim_data = XXrlimit.rlim_cur;} /* soft limit */
|
||
#endif /* BSD42 */
|
||
#endif /* M_WARN */
|
||
|
||
/* On initial startup, get two blocks of each size up to 1k bytes */
|
||
if (!gotpool)
|
||
getpool (), getpool (), gotpool = 1;
|
||
|
||
/* Find current end of memory and issue warning if getting near max */
|
||
|
||
cp = sbrk (0);
|
||
siz = cp - endofpure;
|
||
#ifdef M_WARN
|
||
switch (warnlevel) {
|
||
case 0:
|
||
if (siz > (lim_data / 4) * 3) {
|
||
warnlevel++;
|
||
malloc_warning ("Warning: past 75% of memory limit");}
|
||
break;
|
||
case 1:
|
||
if (siz > (lim_data / 20) * 17) {
|
||
warnlevel++;
|
||
malloc_warning ("Warning: past 85% of memory limit");}
|
||
break;
|
||
case 2:
|
||
if (siz > (lim_data / 20) * 19) {
|
||
warnlevel++;
|
||
malloc_warning ("Warning: past 95% of memory limit");}
|
||
break;}
|
||
#endif /* M_WARN */
|
||
|
||
if ((int) cp & 0x3ff) /* land on 1K boundaries */
|
||
sbrk (1024 - ((int) cp & 0x3ff));
|
||
|
||
/* Take at least 2k, and figure out how many blocks of the desired size we're about to get */
|
||
nblks = 1;
|
||
if ((siz = nu) < 8)
|
||
nblks = 1 << ((siz = 8) - nu);
|
||
|
||
if ((cp = sbrk (1 << (siz + 3))) == (char *) -1)
|
||
return; /* no more room! */
|
||
if ((int) cp & 7) { /* shouldn't happen, but just in case */
|
||
cp = (char *) (((int) cp + 8) & ~7);
|
||
nblks--;}
|
||
|
||
/* save new header and link the nblks blocks together */
|
||
nextf[nu] = (struct mhead *) cp;
|
||
siz = 1 << (nu + 3);
|
||
while (1) {
|
||
((struct mhead *) cp) -> mh_alloc = ISFREE;
|
||
((struct mhead *) cp) -> mh_index = nu;
|
||
if (--nblks <= 0) break;
|
||
CHAIN ((struct mhead *) cp) = (struct mhead *) (cp + siz);
|
||
cp += siz;}
|
||
/* CHAIN ((struct mhead *) cp) = 0; /* since sbrk() returns cleared core, this is already set */
|
||
}
|
||
|
||
static
|
||
getpool () {
|
||
register int nu;
|
||
register char *cp = sbrk (0);
|
||
|
||
if ((int) cp & 0x3ff) /* land on 1K boundaries */
|
||
sbrk (1024 - ((int) cp & 0x3ff));
|
||
|
||
/* Get 2k of storage */
|
||
|
||
cp = sbrk (04000);
|
||
if (cp == (char *) -1)
|
||
return;
|
||
|
||
/* Divide it into an initial 8-word block
|
||
plus one block of size 2**nu for nu = 3 ... 10. */
|
||
|
||
CHAIN (cp) = nextf[0];
|
||
nextf[0] = (struct mhead *) cp;
|
||
((struct mhead *) cp) -> mh_alloc = ISFREE;
|
||
((struct mhead *) cp) -> mh_index = 0;
|
||
cp += 8;
|
||
|
||
for (nu = 0; nu < 7; nu++) {
|
||
CHAIN (cp) = nextf[nu];
|
||
nextf[nu] = (struct mhead *) cp;
|
||
((struct mhead *) cp) -> mh_alloc = ISFREE;
|
||
((struct mhead *) cp) -> mh_index = nu;
|
||
cp += 8 << nu;}}
|
||
|
||
char *
|
||
malloc (n) /* get a block */
|
||
unsigned n; {
|
||
register struct mhead *p;
|
||
register unsigned int nbytes;
|
||
register int nunits = 0;
|
||
|
||
/* Figure out how many bytes are required, rounding up to the nearest
|
||
multiple of 4, then figure out which nextf[] area to use */
|
||
nbytes = (n + sizeof *p + EXTRA + 3) & ~3;
|
||
{
|
||
register unsigned int shiftr = (nbytes - 1) >> 2;
|
||
|
||
while (shiftr >>= 1)
|
||
nunits++;
|
||
}
|
||
|
||
/* If there are no blocks of the appropriate size, go get some */
|
||
/* COULD SPLIT UP A LARGER BLOCK HERE ... ACT */
|
||
if (nextf[nunits] == 0)
|
||
morecore (nunits);
|
||
|
||
/* Get one block off the list, and set the new list head */
|
||
if ((p = nextf[nunits]) == 0)
|
||
return 0;
|
||
nextf[nunits] = CHAIN (p);
|
||
|
||
/* Check for free block clobbered */
|
||
/* If not for this check, we would gobble a clobbered free chain ptr */
|
||
/* and bomb out on the NEXT allocate of this size block */
|
||
if (p -> mh_alloc != ISFREE || p -> mh_index != nunits)
|
||
#ifdef rcheck
|
||
botch ("block on free list clobbered");
|
||
#else
|
||
abort ();
|
||
#endif /* rcheck */
|
||
|
||
/* Fill in the info, and if range checking, set up the magic numbers */
|
||
p -> mh_alloc = ISALLOC;
|
||
#ifdef rcheck
|
||
p -> mh_nbytes = n;
|
||
p -> mh_magic4 = MAGIC4;
|
||
{
|
||
register char *m = (char *) (p + 1) + n;
|
||
|
||
*m++ = MAGIC1, *m++ = MAGIC1, *m++ = MAGIC1, *m = MAGIC1;
|
||
}
|
||
#else
|
||
p -> mh_size = n;
|
||
#endif /* rcheck */
|
||
#ifdef MSTATS
|
||
nmalloc[nunits]++;
|
||
nmal++;
|
||
#endif /* MSTATS */
|
||
return (char *) (p + 1);}
|
||
|
||
free (mem)
|
||
char *mem; {
|
||
register struct mhead *p;
|
||
{
|
||
register char *ap = mem;
|
||
|
||
ASSERT (ap != 0);
|
||
p = (struct mhead *) ap - 1;
|
||
ASSERT (p -> mh_alloc == ISALLOC);
|
||
#ifdef rcheck
|
||
ASSERT (p -> mh_magic4 == MAGIC4);
|
||
ap += p -> mh_nbytes;
|
||
ASSERT (*ap++ == MAGIC1); ASSERT (*ap++ == MAGIC1);
|
||
ASSERT (*ap++ == MAGIC1); ASSERT (*ap == MAGIC1);
|
||
#endif /* rcheck */
|
||
}
|
||
{
|
||
register int nunits = p -> mh_index;
|
||
|
||
ASSERT (nunits <= 29);
|
||
p -> mh_alloc = ISFREE;
|
||
CHAIN (p) = nextf[nunits];
|
||
nextf[nunits] = p;
|
||
#ifdef MSTATS
|
||
nmalloc[nunits]--;
|
||
nfre++;
|
||
#endif /* MSTATS */
|
||
}
|
||
}
|
||
|
||
char *
|
||
realloc (mem, n)
|
||
char *mem;
|
||
register unsigned n; {
|
||
register struct mhead *p;
|
||
register unsigned int tocopy;
|
||
register int nbytes;
|
||
register int nunits;
|
||
|
||
if ((p = (struct mhead *) mem) == 0)
|
||
return malloc (n);
|
||
p--;
|
||
nunits = p -> mh_index;
|
||
ASSERT (p -> mh_alloc == ISALLOC);
|
||
#ifdef rcheck
|
||
ASSERT (p -> mh_magic4 == MAGIC4);
|
||
{
|
||
register char *m = mem + (tocopy = p -> mh_nbytes);
|
||
ASSERT (*m++ == MAGIC1); ASSERT (*m++ == MAGIC1);
|
||
ASSERT (*m++ == MAGIC1); ASSERT (*m == MAGIC1);
|
||
}
|
||
#else
|
||
if (p -> mh_index >= 13)
|
||
tocopy = (1 << (p -> mh_index + 3)) - sizeof *p;
|
||
else
|
||
tocopy = p -> mh_size;
|
||
#endif /* rcheck */
|
||
|
||
/* See if desired size rounds to same power of 2 as actual size. */
|
||
nbytes = (n + sizeof *p + EXTRA + 7) & ~7;
|
||
|
||
/* If ok, use the same block, just marking its size as changed. */
|
||
if (nbytes > (4 << nunits) && nbytes <= (8 << nunits)) {
|
||
#ifdef rcheck
|
||
register char *m = mem + tocopy;
|
||
*m++ = 0; *m++ = 0; *m++ = 0; *m++ = 0;
|
||
p-> mh_nbytes = n;
|
||
m = mem + n;
|
||
*m++ = MAGIC1; *m++ = MAGIC1; *m++ = MAGIC1; *m++ = MAGIC1;
|
||
#else
|
||
p -> mh_size = n;
|
||
#endif /* rcheck */
|
||
return mem;}
|
||
|
||
if (n < tocopy)
|
||
tocopy = n;
|
||
{
|
||
register char *new;
|
||
void bcopy(); /*HMS: here? */
|
||
|
||
if ((new = malloc (n)) == 0)
|
||
return 0;
|
||
bcopy (mem, new, tocopy);
|
||
free (mem);
|
||
return new;
|
||
}
|
||
}
|
||
|
||
#ifdef MSTATS
|
||
/* Return statistics describing allocation of blocks of size 2**n. */
|
||
|
||
struct mstats_value {
|
||
int blocksize;
|
||
int nfree;
|
||
int nused;
|
||
};
|
||
|
||
struct mstats_value
|
||
malloc_stats (size)
|
||
int size; {
|
||
struct mstats_value v;
|
||
register int i;
|
||
register struct mhead *p;
|
||
|
||
v.nfree = 0;
|
||
|
||
if (size < 0 || size >= 30) {
|
||
v.blocksize = 0;
|
||
v.nused = 0;
|
||
return v;}
|
||
|
||
v.blocksize = 1 << (size + 3);
|
||
v.nused = nmalloc[size];
|
||
|
||
for (p = nextf[size]; p; p = CHAIN (p))
|
||
v.nfree++;
|
||
|
||
return v;}
|
||
#endif
|
||
|
||
/* how much space is available? */
|
||
|
||
unsigned freespace() {
|
||
register int i, j;
|
||
register struct mhead *p;
|
||
register unsigned space = 0;
|
||
int local; /* address only is used */
|
||
|
||
space = (char *)&local - sbrk(0); /* stack space */
|
||
|
||
for (i = 0; i < 30; i++) {
|
||
for (j = 0, p = nextf[i]; p; p = CHAIN (p), j++) ;
|
||
space += j * (1 << (i + 3));}
|
||
|
||
return(space);}
|
||
|
||
/* How big is this cell? */
|
||
|
||
unsigned mc_size(cp)
|
||
char *cp;{
|
||
register struct mhead *p;
|
||
|
||
if ((p = (struct mhead *) cp) == 0) {
|
||
/*HMS? */
|
||
}
|
||
p--;
|
||
#ifdef rcheck
|
||
return p -> mh_nbytes;
|
||
#else
|
||
return (1 << (p -> mh_index + 3)) - sizeof *p;
|
||
/**/
|
||
/* if (p -> mh_index >= 13)
|
||
/* return (1 << (p -> mh_index + 3)) - sizeof *p;
|
||
/* else
|
||
/* return p -> mh_size;
|
||
/**/
|
||
#endif /* rcheck */
|
||
}
|
||
|
||
/*HMS: Really should use memcpy, if available... */
|
||
|
||
void bcopy(source, dest, len)
|
||
register char *source, *dest;
|
||
register len; {
|
||
register i;
|
||
|
||
for (i = 0; i < len; i++)
|
||
*dest++ = *source++;}
|